package com.nvyuan.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;

public class NioSelectorServer {
    public static void main(String[] args) throws IOException {
        //创建NIO ServerSocketChannel
        ServerSocketChannel serverSocket = ServerSocketChannel.open();
        serverSocket.socket().bind(new InetSocketAddress(9000));
        //设置ServerSocketChannel为非堵塞
        serverSocket.configureBlocking(false);
        //打开Selector处理Channel，即创建epoll
        Selector selector = Selector.open();
        //把ServerSocketChannel注册到selector 上 ，并且selector 对客户端accept连接操作感兴趣
        serverSocket.register(selector,SelectionKey.OP_ACCEPT);
        System.out.println("服务自动启动");

        while (true){
            //阻塞等待需要处理的事件发生
            selector.select();
            //获取selector中注册的全部事件的SelectionKey 实例
            Set<SelectionKey> selectionKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = selectionKeys.iterator();
            //遍历SelectionKey对事件进行处理
            while (iterator.hasNext()){
                SelectionKey key = iterator.next();
                //如果是OP_ACCEPT事件，则进行连接获取和事件注册
                if(key.isAcceptable()){
                    ServerSocketChannel server = (ServerSocketChannel) key.channel();
                    SocketChannel socketChannel = server.accept();
                    socketChannel.configureBlocking(false);
                    //这里只注册了读事件，如果需要给客户发送数据可以注册写事件
                    socketChannel.register(selector,SelectionKey.OP_READ);
                    System.out.println("客户端连接成功");


                }else if(key.isReadable()){
                    //如果是OP_READ事件，则进行读取和打印
                    SocketChannel socketchannel = (SocketChannel) key.channel();
                    ByteBuffer byteBuffer = ByteBuffer.allocate(128);
                    int len = socketchannel.read(byteBuffer);
                    if(len>0){
                        System.out.println("接收消息："+new String(byteBuffer.array()));
                    }else if(len==-1){
                        //客户端断开了连接,关闭socket
                        System.out.println("客户端断开了连接");
                        socketchannel.close();
                    }

                }
                //从事件集合里删除本地处理的key，防止下次select重复处理
                iterator.remove();

            }


        }




    }





}
